1. Field of the Invention
The present invention relates to a sensor device, and more particularly, to a sensor device for determining a running speed or the like of a bicycle.
2. Description of the Background Art
Measuring devices for a running speed or the like of a bicycle have conventionally been known.
For example, Japanese Patent Laying-Open No. 2005-067354 discloses a measuring device having a measurement body portion arranged at a portion where a rear wheel and a gear crank of a bicycle are positioned, and a display portion arranged at a position in a field of vision of a rider of the bicycle for displaying predetermined information based on a signal transmitted from the measurement body portion.
The measurement body portion has a first sensor portion for detecting movement of a predetermined part of the gear crank to determine a cadence at which a pedal is moving, a second sensor portion for detecting movement of a predetermined part of the rear wheel to determine a running speed of the bicycle, and a transmitting portion electrically connected to the first and second sensor portions for wirelessly transmitting signals detected by the first and second sensor portions to the display portion.
When a sensor portion for detecting movement of a predetermined part in a bicycle is fixed on a front fork or a chain stay of the bicycle, it is necessary to adjust the distance between the fixed sensor portion and the predetermined part. To facilitate the fixation of the sensor portion and adjustment of the distance, a member rotatably holding the sensor portion is required.
On the other hand, there may be a case where the space for attaching a sensor device to a bicycle does not have sufficient room (for example, when a sensor portion is fixed on a front fork). Accordingly, downsizing of a sensor device for a bicycle is required.
Further, in another respect, it is also required to reduce the number of parts to downsize a sensor device.